This invention relates to electrically erasable programmable read-only-memory (EEPROM) semiconductor memory device programmers and deals more particularly with an EEPROM programmer in which the EEPROM is part of an alphanumeric display system.
EEPROM nonvolatile semiconductor memories are used extensively as program stores in microprocessor based systems due to their ability to be reprogrammed electrically at an on-site location without removal from in-service equipment. The techniques for reprogramming EEPROMs in such microprocessor systems are generally well known in the art. However, in non-microprocessor based systems, the EEPROM must often be removed from the in-service equipment and memory alteration must be accomplished using programming apparatus and techniques also well known in the art.
Generally, in both instances above, the data to be programmed is entered into the EEPROM in an a binary coded format. In order to verify the entered data, the contents of each cell location in the EEPROM must be read and compared to the desired code assigned to the corresponding cell location. The verification procedure is time consuming and subject to error when done manually because a person doing the verification must often use an encoded listing rather than a much simpler to read and understand alphanumeric representation of the code. The entries may also be verified by a computer-based system which contains a listing of the encoded information for each cell and which can access each cell location and compare the actual cell contents to the listed encoded information. However, such computer-based systems are generally remotely located from the equipment site and are costly. Also the use of such systems generally requires additional apparatus to generate the code listing to be read.
A feature of the present invention is that an EEPROM can be programmed using an EEPROM based alphanumeric display system.
Another feature of the present invention is that the programming of an EEPROM and the verification of programmed data can be accomplished without the necessity of additional and often costly apparatus.
Another feature of the present invention allows the user to verify a data entry by viewing the alphanumeric character representation of the coded entry on the display device of the display system.
Other features and advantages of the present invention will be apparent from the following written description and from the drawings forming a part hereof.